My client is building a tool that makes it easier to fill in certain types of web forms found on third-party websites. They would like to provide help for the user while the user is filling in the forms, which might be multi-page. Additionally, they'd like the user to return to their site when they've finished the form so they can move to the next step.

The goals are these:

  • Minimize confusion among users about jumping to 3rd-party sites
  • Provide resources only available on the parent site (instructions, etc.)
  • Ensure the user ends up back at the parent site to complete the overall task they're involved with

The client initially envisioned this as an iframe that sits atop the page and provides instructions, account numbers, navigation, etc.

We'd like to avoid using an iframe, though, for the usual reasons. (Breaks the back button, etc.)

What are some alternatives?

  • I'm struggling to understand the bigger picture here...seems that trying to offer '3rd party help' for a form is likely going to make the initial form experience more difficult.
    – DA01
    Commented Jun 13, 2014 at 17:33
  • DA01, think exceedingly complex government or tax forms being filled in by laypeople.
    – Yossi
    Commented Jun 13, 2014 at 22:11
  • 1
    at that level, I think offering a PDF of instructions may be the most usable solution. The end-user can then open it up and put it next to their browser as they go (or print it out). There's no way you can technically connect to something like an IRS form though and inject 3rd party hep content.
    – DA01
    Commented Jun 13, 2014 at 22:25

2 Answers 2


The only two possibilities that come to my mind as allowed by general web security constraints, are:

  • Developing agreements with original form owners about redirecting users back to your website. The costs of adjusting such websites (additional code might be required to [a] recognize you as the one who forwarded the user, [b] return user back to you) and of getting and maintaining such agreements might be significant, though. Examples: countless online payment systems, which offer forms prefilled by web stores - and return users back to store upon payment completion.

  • Proxying the complete user experience, ie. your code reads the endpoint form, reparses it and presents to user, and upon filling and submitting it by user - your code forwards the content to the endpoint website, gets the result, reparses it, presents to user... and so on. This, however, raises several security issues and might cause users to mistrust your website. Example (quite extreme): Sofort Banking, an online money transfer system that uses bank credentials provided by user to perform account operations on his account, using his bank's original web interface.

Additionaly, neither IFRAME nor redirection to the endpoint site would allow you to prefill the form, unless such form allows that by some POST/GET interface. The common security constraints in web browsers totally forbid such behaviour. There are some exploits occasionally, but those are quickly fixed in decent products.


Personally agree with the iframe method as it allows the user to know that going to the other site is part of the process without requiring too much to learn. Facebook does this for single sign on (Facebook Login), LinkedIn does this for submitting resume information, and so on.

The alternative to this is doing this through a popup. Popups as we know can be blocked by the browsers which can sometimes be frustrating. Popups can sometimes be seen as intrusive or confusing especially if it goes to a 3rd party site few know about.

When filling out forms, in general the back button isn't something you'd want the user to utilize. You can manage the steps and navigation between steps yourself in your form wizard. By placing forward and back buttons directly on the form (above or below) where the user will be inputting their information, you will be able to avoid any issues that are a result of user hitting back or forward. On top of avoiding issues, you can ensure that users have the ability to leave the form from the 3rd party site at any time as well without breaking your flow and potentially losing a user.

  • 1
    iFrame may be the only plausible solution, but do note that there are likely hurdles with this as well...namely frame busting scripts and https 3rd party sites.
    – DA01
    Commented Jun 13, 2014 at 17:33
  • There are certainly hurdles to overcome with any solution. When it comes to user experience though, getting past those hurdles is all the fun ;) Commented Jun 14, 2014 at 3:06

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